<template>
    <canvas ref="canvas" @click="updateCode" :style="{width: contentWidth+'px',height:contentHeight+'px'}" :width="contentWidth" :height="contentHeight"></canvas>
</template>
<script>
    export default {
        name: 'v-captch',
        props: {

            value: {
                type: String
            },
            fontSizeMin: {
                type: Number,
                default: 25
            },
            fontSizeMax: {
                type: Number,
                default: 30
            },
            backgroundColorMin: {
                type: Number,
                default: 255
            },
            backgroundColorMax: {
                type: Number,
                default: 255
            },
            colorMin: {
                type: Number,
                default: 0
            },
            colorMax: {
                type: Number,
                default: 160
            },
            lineColorMin: {
                type: Number,
                default: 100
            },
            lineColorMax: {
                type: Number,
                default: 255
            },
            dotColorMin: {
                type: Number,
                default: 0
            },
            dotColorMax: {
                type: Number,
                default: 255
            },
            contentWidth: {
                type: Number,
                default: 112
            },
            contentHeight: {
                type: Number,
                default: 31
            },
            codeNumber:{
                type:Number,
                default:4
            }

        },
        methods: {
            // 生成一个随机数
            randomNum(min, max) {
                return Math.floor(Math.random() * (max - min) + min)
            },
            // 生成一个随机的颜色
            randomColor(min, max) {
                let r = this.randomNum(min, max)
                let g = this.randomNum(min, max)
                let b = this.randomNum(min, max)
                return 'rgb(' + r + ',' + g + ',' + b + ')'
            },
            drawPic() {
                let canvas = this.$refs.canvas; //document.getElementById('s-canvas')
                let ctx = canvas.getContext('2d')
                ctx.textBaseline = 'bottom'
                // 绘制背景
                ctx.fillStyle = this.randomColor(this.backgroundColorMin, this.backgroundColorMax)
                ctx.fillRect(0, 0, this.contentWidth, this.contentHeight)
                // 绘制文字
                for (let i = 0; i < this.value.length; i++) {
                    this.drawText(ctx, this.value[i], i)
                }
                this.drawLine(ctx)
                this.drawDot(ctx)
            },
            drawText(ctx, txt, i) {
                ctx.fillStyle = this.randomColor(this.colorMin, this.colorMax)
                ctx.font = '16px SimHei'
                let x = (i) * (this.contentWidth / (this.value.length + 1))

                let y = this.randomNum(this.fontSizeMax, this.contentHeight - 5)

                var deg = 0//this.randomNum(-45, 45)
                // 修改坐标原点和旋转角度
                ctx.translate(x, y)
                ctx.rotate(deg * Math.PI / 180)
                ctx.fillText(txt, 0, 0)
                // 恢复坐标原点和旋转角度
                ctx.rotate(-deg * Math.PI / 180)
                ctx.translate(-x, -y)
            },
            drawLine(ctx) {
                // 绘制干扰线
               /* for (let i = 0; i < 5; i++) {
                    ctx.strokeStyle = this.randomColor(this.lineColorMin, this.lineColorMax)
                    ctx.beginPath()
                    ctx.moveTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight))
                    ctx.lineTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight))
                    ctx.stroke()
                }*/
            },
            drawDot(ctx) {
                // 绘制干扰点
                /*for (let i = 0; i < 80; i++) {
                    ctx.fillStyle = this.randomColor(0, 255)
                    ctx.beginPath()
                    ctx.arc(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight), 1, 0, 2 * Math.PI)
                    ctx.fill()
                }*/
            },
            updateCode(){
                this.$emit('input' , this.getCode());
            },
            getCode(){
                var result = '';
                for (var i=0;i<this.codeNumber;i++)
                {
                    result+=this.randomNum(0,10);
                }
                return result;
            }
        },
        watch: {
            value() {
                this.drawPic()
            }
        },
        mounted() {
            if(this.value == ''){
                this.$emit('input' , this.getCode());
            }else{
                this.drawPic()
            }
            //this.drawPic()
        }
    }
</script>
<style scoped>
    .s-canvas {
        height: 38px;
        position: absolute;
        right: 0px;
        top: 0px;
    }
    .s-canvas canvas{
        margin-top: 1px;
        margin-left: 8px;
    }
</style>
